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From zsxwing <...@git.apache.org>
Subject [GitHub] spark pull request: SPARK-1932: Fix race conditions in onReceiveCa...
Date Tue, 27 May 2014 03:03:08 GMT
GitHub user zsxwing opened a pull request:

    https://github.com/apache/spark/pull/887

    SPARK-1932: Fix race conditions in onReceiveCallback and cachedPeers

    `var cachedPeers: Seq[BlockManagerId] = null` is used in `def replicate(blockId: BlockId,
data: ByteBuffer, level: StorageLevel)` without proper protection.
    
    There are two place will call `replicate(blockId, bytesAfterPut, level)`
    * https://github.com/apache/spark/blob/17f3075bc4aa8cbed165f7b367f70e84b1bc8db9/core/src/main/scala/org/apache/spark/storage/BlockManager.scala#L644
runs in `connectionManager.futureExecContext`  
    * https://github.com/apache/spark/blob/17f3075bc4aa8cbed165f7b367f70e84b1bc8db9/core/src/main/scala/org/apache/spark/storage/BlockManager.scala#L752
`doPut` runs in `connectionManager.handleMessageExecutor`. `org.apache.spark.storage.BlockManagerWorker`
calls `blockManager.putBytes` in `connectionManager.handleMessageExecutor`.
    
    As they run in different `Executor`s, this is a race condition which may cause the memory
pointed by `cachedPeers` is not correct even if `cachedPeers != null`.
    
    The race condition of `onReceiveCallback` is that it's set in `BlockManagerWorker` but
read in a different thread in `ConnectionManager.handleMessageExecutor`.


You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/zsxwing/spark SPARK-1932

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/spark/pull/887.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #887
    
----
commit 524f69cf66473fe3cf0a38789140e6ee6ca57802
Author: zsxwing <zsxwing@gmail.com>
Date:   2014-05-26T17:04:03Z

    SPARK-1932: Fix race conditions in onReceiveCallback and cachedPeers

----


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